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hrtimer: Keep pointer to first timer and simplify __remove_hrtimer()

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__remove_hrtimer() needs to evaluate the expiry time to figure out
whether the timer which is removed is eventually the first expiring
timer on the cpu. Keep a pointer to it, which is lazily updated, so we
can avoid the evaluation dance and retrieve the information from there.

Generates slightly better code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203501.752838019@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Thomas Gleixner 2015-04-14 21:08:49 +00:00
parent b97f44c9b6
commit 895bdfa793
2 changed files with 34 additions and 18 deletions
Download patch file Download diff file Expand all files Collapse all files

6
include/linux/hrtimer.h
View file

@ -172,6 +172,7 @@ enum hrtimer_base_type {
* @clock_was_set_seq: Sequence counter of clock was set events
* @expires_next: absolute time of the next event which was scheduled
* via clock_set_next_event()
* @next_timer: Pointer to the first expiring timer
* @in_hrtirq: hrtimer_interrupt() is currently executing
* @hres_active: State of high resolution mode
* @hang_detected: The last hrtimer interrupt detected a hang
@ -180,6 +181,10 @@ enum hrtimer_base_type {
* @nr_hangs: Total number of hrtimer interrupt hangs
* @max_hang_time: Maximum time spent in hrtimer_interrupt
* @clock_base: array of clock bases for this cpu
*
* Note: next_timer is just an optimization for __remove_hrtimer().
* Do not dereference the pointer because it is not reliable on
* cross cpu removals.
*/
struct hrtimer_cpu_base {
raw_spinlock_t lock;
@ -191,6 +196,7 @@ struct hrtimer_cpu_base {
hres_active : 1,
hang_detected : 1;
ktime_t expires_next;
struct hrtimer *next_timer;
unsigned int nr_events;
unsigned int nr_retries;
unsigned int nr_hangs;